lm_test <-
    function (formula, data, subset, weights, na.action, method = "qr",
              model = TRUE, x = FALSE, y = FALSE, qr = TRUE, singular.ok = TRUE,
              contrasts = NULL, offset, ...)
{
    ret.x <- x,
    ret.y <- y
    cl <- match.call()
    mf <- match.call(expand.dots = FALSE)
    m <- match(c("formula", "data", "subset", "weights", "na.action",
                 "offset"), names(mf), 0L)
    mf <- mf[c(1L, m)]
    mf$drop.unused.levels <- TRUE
    mf[[1L]] <- as.name("model.frame")
    mf <- eval(mf, parent.frame())
    if (method == "model.frame")
        return(mf)
    else if (method != "qr")
        warning(gettextf("method = '%s' is not supported. Using 'qr'",
                         method), domain = NA)
    mt <- attr(mf, "terms")
    y <- model.response(mf, "numeric")
    w <- as.vector(model.weights(mf))
    if (!is.null(w) && !is.numeric(w))
        stop("'weights' must be a numeric vector")
    offset <- as.vector(model.offset(mf))
    if (!is.null(offset)) {
        if (length(offset) != NROW(y))
            stop(gettextf("number of offsets is %d, should equal %d (number of observations)",
                          length(offset), NROW(y)), domain = NA)
    }
    if (is.empty.model(mt)) {
        x <- NULL
        z <- list(coefficients = if (is.matrix(y)) matrix(, 0,
                    3) else numeric(0L), residuals = y, fitted.values = 0 *
                  y, weights = w, rank = 0L, df.residual = if (!is.null(w)) sum(w !=
                                               0) else if (is.matrix(y)) nrow(y) else length(y))
        if (!is.null(offset)) {
            z$fitted.values <- offset
            z$residuals <- y - offset
        }
    }
    else {
        x <- model.matrix(mt, mf, contrasts)
        z <- if (is.null(w))
            lm.fit(x, y, offset = offset, singular.ok = singular.ok,
                   ...)
        else lm.wfit(x, y, w, offset = offset, singular.ok = singular.ok,
                     ...)
    }
    class(z) <- c(if (is.matrix(y)) "mlm", "lm")
    z$na.action <- attr(mf, "na.action")
    z$offset <- offset
    z$contrasts <- attr(x, "contrasts")
    z$xlevels <- .getXlevels(mt, mf)
    z$call <- cl
    z$terms <- mt
    if (model)
        z$model <- mf
    if (ret.x)
        z$x <- x
    if (ret.y)
        z$y <- y
    if (!qr)
        z$qr <- NULL
    z
}
